1. Field of the Invention
The present invention relates to the field of molecular biology and nucleic acid chemistry. More specifically, it relates to methods and reagents genotyping at the Glycophorin A locus.
2. Description of Related Art
Glycophorin A (GYPA) is one of the major sialoglycoproteins of the hyman erythrocyte membrane. Glycophorin A carries the M or N blood group antigen, which is determined by the amino acids at residues 1 and 5. A structural comparison of glycophorin proteins and an immunochemical analysis of genetic variants is described in Furthmayr, 1978, Nature 271:519-524.
Glycophorin A is encoded by a gene on human chromosome 4 which consist of 7 exons. The structural organization of the Glycophorin A gene is described in Kudo and Fukuda, 1989, Proc. Natl. Acad. Sci. USA 86:4619-4623, incorporated herein by reference. The nucleotide sequences of the Glycophorin A alleles that encode the proteins that carry the M and N blood group antigens are reported in Siebert and Fukuda, 1987, Proc. Natl. Acad. Sci. USA 84:6735-6739.
The invention of the polymerase chain reaction (PCR), a method for amplifying specific sequences of nucleic acids, makes possible the rapid demotion of nucleic acids present in a sample in what was previously an undetectably low quantity (see U.S. Pat. Nos. 4,683,195; 4,683,202; and 4,965,188, each of which is incorporated herein by reference). Direct detection of an amplified nucleic acid sequence by hybridization with a sequence-specific oligonucleotide probe makes possible the detection of single nucleotide changes in sequence. The detection of allelic nucleotide sequence variations by hybridization of amplified gene nucleic acid sequences with allele-specific nucleic acid probes is described in Saiki et al., 1986, Nature 324:163-166.
One application of genetic typing is the identification of individuals. The use of PCR amplification and nucleic acid probes has revolutionized the field of forensic serology (see Reynolds and Sensabaugh 1991, Anal. Chem. 63:2-15). With PCR and other nucleic acid amplification methods, DNA typing can now be done with samples that contain insufficient DNA for typing by any other means. For example, single hairs provide enough DNA for PCR-based DNA typing. (Higuchi et al., 1988, Nature 332:543-546).
The discriminative power of a DNA genotyping assay depends on the number and frequency of alleles found at a locus. The discovered of additional alleles along with sequence specific probes capable of detecting the alleles at the Glycophorin A locus would substantially improve the discriminative power of a Glycophorin A DNA typing assay and thereby improve its utility in forensic methodology.